I have an iPhone, not an Android
The mobi file with both KF7, KF8 and kindlegen source file works fine on my iPhone. Just the KF8 only file which has download issues. So perhaps the iPhone Kindle app does not have KF8 support.
Will try this evening on my Kindle Touch 3G to download the KF8 only file to check if it works. My parcel awaits me at home